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advantage, which receives the full Charge of air from the open door-way, the air being distributed through a number of small holes inthe front of the curtain plate.
Other methods have been tried to effect complete combustion.One method (Fig. 386) consists of a small fire box placed at theback of an ordinary fire box; this plan is introduced for burningcoal and coke, the latter being placed in the large fire box. Thecoal being consumed in the auxiliary fire box, the smoke and gases
Fig. 386. —Auxiliary Fire Box. a, Small fire box. b, Fire box. C, Fire tile. d, Body of boilershowing tubes. ee, Dampers. f, Furnace door.
evolved pass through small short tubes into the main fire box, andare caused to make an upward direction through the interpositionof a fire tile, thus passing over the entire length of the incandescentfuel in the main box before entering the small tubes in the body ofthe boiler.
Another method was designed to burn coal alone. The firegrate, as in a previous example, is large, and is divided by aninclined water space into two compartments, having a separatedoor, fire grate, ash pan, and damper for each; the largest gratebeing at the back, near the foot plate. The flarae and gases fromthis fire box rise, and, being met by a fine current of air entering